1. Field of the Invention
This invention relates generally to a seal and a valve, and more particularly to a seal assembly for use in gate valves.
2. The Prior Art
Typical current seals used in gate valves include a metallic valve seat that is press fit into a valve body. A resilient sealing element is force fit into the valve seat and held in position in an annular groove, which may include serrations. When the resilient seal element experiences wear, it is common to replace not only that element but the valve seat also, due to the difficulty in removing the seal element from the seat. Accordingly, this procedure is not only time consuming from the standpoint of removing the entire valve seat from the valve body, but is also unnecessarily expensive as a result of replacing two components in the assembly.
Various prior art efforts have been attempted to alleviate these problems. For example, U.S. Pat. No. 3,273,855 to Wells discloses sealing ring members which retain a resilient seal member in position in a gate valve assembly. However, the particular arrangement disclosed in this patent is not well suited for mid-range to high-range pressure operation. Also, the specific arrangement in Wells for maintaining the seal in position is difficult to machine and may not effectively hold the seal in place during the sliding movement of the gate element.
Other alternative sealing ring and seal arrangements are disclosed in U.S. Pat. Nos. 2,925,247 to Fletcher and 564,378 to Jennings, but these likewise include similar drawbacks as noted in connection with the Wells patent. Various other prior art attempts are disclosed in U.S. Pat. Nos. 3,175,802, to Bredtschneider, 3,929,316 to Guthrie, 4,116,419 to Diehl, 3,006,601 to Anderson, and 1,874,405 to Wood.
Accordingly, none of the prior art efforts have provided a valve seat and seal arrangement particularly suited for mid-range to high-range internal pressures, nor do they provide a structural relationship between the retaining ring and the seal for positively and effectively maintaining the seal in position during use.